Area Forecast Discussion
Issued by NWS Billings, MT
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Issued by NWS Billings, MT
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-- Discussion containing changed information from previous version are highlighted. --883 FXUS65 KBYZ 012122 AFDBYZ Area Forecast Discussion National Weather Service Billings MT 322 PM MDT Wed May 1 2024 .DISCUSSION...-- Changed Discussion --Rest of Today through Friday Night... Unsettled and cool conditions will continue through the rest of the work week as we remain under the influence of an upper low to our north. The scattered showers and isolated thunderstorms today will gradually tapper off through the evening and overnight hours providing a dry period before precipitation chances increase again Thursday (20-70% chance, highest north of Billings). During this dry period overnight, winds will increase over the western foothills with 30 to 40 mph gusts expected from Big Timber to Harlowton. These winds will gradually back off by through the morning hours, but mix down winds will allow 20-30 mph winds to pick up across the region Thursday. While chances of precipitation will be less on Friday, unstable cyclonic flow will allow low to moderate chances over south central MT through the day (15-60%, highest over the mountains). With this, breezy northwest winds will pick back up, with 15 to 30 mph gusts expected through the day. Rising heights Friday evening and night will kick off a brief drying and warming period across the region. The precipitation through the rest of the week will mainly be light rain over the lower elevations, including Billings. A mix of rain and snow is possible over the higher hills of the lower elevations, including Hysham Hills, Lame Deer Divide, and Government Hill, but travel impacts look little to none with above freezing temperatures. Temporary reductions in visibility is the main concern with this activity. With snow levels generally around 4000-5000 feet during the day and 3000-4000 feet overnight, snow is expected in the mountains and immediate foothills. Accumulations will be light through the rest of the week, with high chances for liquid precipitation to amount to 0.15 inches or less over the lower elevations. In the mountains, generally 1-4 inches of snow is expected. A more dynamic and impactful system is possible early next week. See the long-term discussion for details. Arends Saturday through Wednesday... On Saturday, models agree on a 500 mb flow pattern consisting of a shortwave ridge over the Northern Rockies. This ridge will bring dry weather to the area. In addition, we will be located between surface high pressure over the northern Plains and low pressure over the Pacific Northwest, which means that a surface pressure gradient will develop with the low-level flow turning southeasterly and facilitating warming via some warm air advection and compressional warming. Saturday night into Sunday, an upper low will move eastward over the Pacific Northwest/west-central US, with an increasing probability of precipitation (PoP) from west to east over southern MT and north central WY. Sunday afternoon, latest NBM shows PoP values ranging from around 15% over southeast MT to 50-60% in the foothills and mountains west of Billings. Precipitation would occur in the form of showers and a few isolated thunderstorms. Any snow during this time would be confined to locations above 8500-9500 feet. Continued low-level southeasterly flow should cause more warming for central and eastern areas. Sunday night into Monday night, models have come into somewhat better agreement on a dynamic upper low moving from the Pacific Northwest/west-central US to the northern Plains/southern Canada area. There is still some uncertainty with the exact track of the low, which will affect how much precipitation falls in our area. Ensemble mean solutions do show near to above normal precipitable water values in our area, indicating increased moisture availability for this system. NBM shows probability of receiving at least 0.50 inches of precipitation ranges from 20% over areas west/northwest of Billings and southeastern Carbon County to 40-50% over southeast MT to 50-60% in the mountains. Precipitation for most of the area will be rain with a few embedded, isolated thunderstorms, but snow will fall above 6000 to 7000 feet elevation. In addition, ensemble means show the sea-level pressure of the low dropping to about 985-990 mb, with some solutions even going to ~981 mb over eastern MT, which would support windy conditions in our area, with wind gusts reaching 30-50 mph, strongest in southeast MT, late Monday afternoon into Monday night. So, a wind-driven rain is probable with this system. Tuesday into Wednesday, the Northern Rockies look to remain under large-scale troughing but west of the dynamic upper low. This pattern favors cool and unsettled weather, with periods of showers. PoP values for Tuesday are 40-60%, and for Wednesday are 30-60%, greatest in the mountains. High temperatures will generally be in the 60s-70s Saturday, 60s-80s Sunday (warmest in southeast MT), and 50s-60s Monday, Tuesday and Wednesday. RMS-- End Changed Discussion --&& .AVIATION...-- Changed Discussion --Scattered showers and isolated thunderstorms will occur this afternoon then diminish overnight. Winds will be gusty over south central MT into this evening then should diminish overnight for most areas outside the western foothills, where winds will gust to 20-30 kt. In addition, the showers and thunderstorms can produce gusty winds to about 30 kt. On Thursday, scattered showers and isolated thunderstorms will develop first for areas north of KLVM-K6S0-KBIL in the morning, then expand southward for much of the area after 18z Thursday. Local MVFR conditions are possible in the heavier showers and thunderstorms. Thursday will be windy with gusts to 30 kt, and wind direction changing from WSW in the morning to WNW/NW from late morning through the afternoon. Mountains will be obscured in clouds and snow showers into Thursday. RMS-- End Changed Discussion --&& .PRELIMINARY POINT TEMP/POPS...-- Changed Discussion --Thu Fri Sat Sun Mon Tue Wed ----------------------------------------------------------- BIL 033/053 033/055 032/069 045/075 047/060 042/059 041/059 15/O 23/O 00/B 03/W 56/W 34/W 34/W LVM 029/050 029/054 030/066 042/067 041/054 038/053 037/056 34/R 33/O 00/B 15/T 66/W 34/W 34/W HDN 030/055 030/056 029/072 045/080 045/062 040/059 038/060 25/R 22/O 00/U 02/T 56/W 44/W 34/W MLS 032/052 032/052 029/069 046/082 052/066 042/055 039/059 14/T 21/E 00/U 01/N 47/T 64/W 33/W 4BQ 032/055 030/053 029/070 047/081 049/065 040/054 037/056 32/R 11/B 00/U 01/N 47/T 54/W 33/W BHK 029/054 030/051 027/064 042/075 049/067 040/055 037/058 34/T 21/N 00/U 01/N 47/T 65/W 33/W SHR 025/054 027/053 028/069 043/078 042/059 038/057 035/057 53/R 23/R 00/U 02/W 57/W 44/W 33/W-- End Changed Discussion --&& .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$ weather.gov/billings